A typical disc drive includes a base to which various components of the disc drive are mounted. The components include a spindle motor, which rotates one or more discs at a constant high speed. Information is written to and read from tracks on the discs through the use of an actuator assembly, which rotates during a seek operation about a bearing shaft assembly positioned adjacent the discs. The actuator assembly may include a plurality of actuator arms, which extend towards the discs, with one or more head gimbal assemblies extending from each of the actuator arms. Each head gimbal assembly includes a flexure or load beam and a head mounted at the distal end of the load beam. Each head includes an air bearing slider enabling the head to fly in close proximity above the corresponding surface of the associated disc. Head gimbal assemblies are typically attached to the corresponding metallic actuator arms by a metallic spring member spot welded to the metallic load beams and to the metallic actuator arms. The spring member biases the head gimbal assembly towards the surface of the disc.
During a seek operation, the track position of the heads is controlled through the use of a voice coil motor, which typically includes a coil attached to the actuator assembly, as well as one or more permanent magnets, which establish a magnetic field in which the coil is immersed. Application of current to the coil causes the coil to move. As the coil moves, the actuator assembly pivots about the bearing shaft assembly, and the heads are caused to move across the surfaces of the discs.
A circuit assembly provides the requisite electrical connection paths for the actuator assembly while allowing pivotal movement of the actuator assembly during operation. The flex assembly includes a printed circuit board to which head wires (not shown) are connected; the head wires being routed along the actuator arms and the load beams to the heads. The printed circuit board typically includes circuitry for controlling the write currents applied to the heads during a write operation and a preamplifier for amplifying read signals generated by the heads during a read operation.
The head wires, the printed circuit board, the actuator arms, and the coil are all separate parts that must be assembled during manufacturing of the disc drive. The assembly and the cost of manufacturing the separate components add to the overall cost of manufacturing the disc drive.
Additionally, vibrations in the disc drive, particularly in the actuator arms and the head gimbal assemblies, can have an adverse effect on drive reliability by creating unpredicted movement between the head and the disc. Such unpredicted movement can cause read/write errors. Additionally, such movement prevents narrower tracks from being used in disc drives, and thus limits the memory capability of the disc drive. To decrease the vibrations in the actuator arms, the arms are typically constructed with resonant frequencies that are well above the driving frequencies of the disc drive.
Accordingly, there is a need for a disc drive actuator assembly that decreases the costs of manufacture and that decreases vibrations of the actuator arms and head gimbal assemblies. The present invention provides a solution to these and other problems, and offers other advantages over the prior art.